Do all traits within an organism age for the same reason? Evolutionary theories of aging share a common assumption: the strength of natural selection declines with age. A corollary is that additive genetic variance should increase with age. However, not all senescent traits display such increases suggesting that other mechanisms may be at play. Using longitudinal data collected from more than 5...

This work aims to estimate the genetic parameters of seminal and production traits in a paternal line of rabbits selected for ADG during the fattening period. The considered traits were male libido (Lib) defined as successful mounting of an artificial vagina; presence of urine (Ur) and calcium carbonate deposits (Ca) in the ejaculate; semen pH; individual sperm motility (IM); the suitability fo...

Sperm are the most diverse cell type known: varying not only among- and within- species, but also among- and within-ejaculates of a single male. Recently, the causes and consequences of variability in sperm phenotypes have received much attention, but the importance of within-ejaculate variability remains largely unknown. Correlative evidence suggests that reduced within-ejaculate variation in ...

BACKGROUND Strict genetic monogamy leads to sexual harmony because any trait that decreases the fitness of one sex also decreases the fitness of the other. Any deviation from monogamy increases the potential for sexual conflict. Conflict is further enhanced by sperm competition, and given the ubiquity of this phenomenon, sexual conflict is rife. In support of theory, experimentally enforced mon...

Bacteria present in ejaculates can impair sperm function and reduce male reproductive success. Thus, selection should favour the evolution of antimicrobial defences to limit the detrimental effects of sperm-associated bacteria. Additionally, current hypotheses suggest that ornamental traits may signal information about the infection status of an individual or the ability of an individual to res...

The fossil record of marine animals suggests that diversity-dependent processes exerted strong control on biodiversification: after the Ordovician Radiation, genus richness did not trend for hundreds of millions of years. However, diversity subsequently rose dramatically in the Cretaceous and Cenozoic (145 million years ago-present), indicating that limits on diversification can be overcome by ...

Honeybee males produce ejaculates consisting of large numbers of high quality sperm. Because queens never re-mate after a single mating episode early in life, sperm are stored in a specialised organ for years but the proximate mechanisms underlying this key physiological adaptation are unknown. We quantified energy metabolism in honeybee sperm and show that the glycolytic metabolite glyceraldeh...

Lipids are the main structural/functional components of the sperm, and their composition may undergo a series of modifications in relation to either physiologic events and/or diet. The effect of lecithin supplementation on reproductive and reproductive performance were studied in rabbits bucks. Twenty eight adult V line rabbits (at age between 7-8 months) were divided into four equal groups. Th...

This study aimed to investigate the differences among four medium breeds of rabbits (Rex, New Zealand White, California and Baladi Red) in productive performance and semen characteristics. Hundred twenty does, 7–9 months of age and 3–3.5 kg body weight from Rex, NZW, California, and Baladi Red. The numbers of 360 parities were analyzed to evaluate breeds effects. Traits studed were litter size ...

Mouse sperm produce enough ATP to sustain motility by anaerobic glycolysis and respiration. However, previous studies indicated that an active glycolytic pathway is required to achieve normal sperm function and identified glycolysis as the main source of ATP to fuel the motility of mouse sperm. All the available evidence has been gathered from the studies performed using the laboratory mouse. H...